Semiconductor structure made using improved pseudo-simultaneous multiple ion implantation process

ABSTRACT

Methods and apparatus provide for: a source simultaneously producing first plasma, which includes a first species of ions, and second plasma, which includes a second, differing, species of ions; an accelerator system including an analyzer magnet, which cooperate to simultaneously: (i) accelerate the first and second plasma along an initial axis, (ii) alter a trajectory of the first species of ions from the first plasma, thereby producing at least one first ion beam along a first axis, which is transverse to the initial axis, and (iii) alter a trajectory of the second species of ions from the second plasma, thereby producing at least one second ion beam along a second axis, which is transverse to the initial axis and the first axis; and a beam processing system operating to simultaneously direct the first and second ion beams toward a semiconductor wafer such that the first and second species of ions bombard an implantation surface of the semiconductor wafer to create an exfoliation layer therein.

BACKGROUND

The features, aspects and embodiments disclosed herein relate to themanufacture of semiconductor devices, such as semiconductor-on-insulator(SOI) structures, using an improved multiple ion implantation processwhereby multiple ion species are implanted in a pseudo-simultaneousfashion.

To date, the semiconductor material most commonly used insemiconductor-on-insulator structures has been silicon. Such structureshave been referred to in the literature as silicon-on-insulatorstructures and the abbreviation “SOI” has been applied to suchstructures. SOI technology is becoming increasingly important for highperformance thin film transistors, solar cells, thermo-electricconversion devices, and displays, such as active matrix displays. SOIstructures may include a thin layer of substantially single crystalsilicon on an insulating material.

Various ways of obtaining SOI structures include epitaxial growth ofsilicon (Si) on lattice matched substrates. An alternative processincludes the bonding of a single crystal silicon wafer to anothersilicon wafer on which an oxide layer of SiO₂ has been grown, followedby polishing or etching of the top wafer down to, for example, a 0.05 to0.3 micron layer of single crystal silicon. Further methods includeion-implantation methods in which either hydrogen or oxygen ions areimplanted either to form a buried oxide layer in the silicon wafertopped by Si in the case of oxygen ion implantation or to separate(exfoliate) a thin Si layer to bond to another Si wafer with an oxidelayer as in the case of hydrogen ion implantation.

Manufacture of SOI structures by these methods is costly. The lattermethod involving hydrogen ion implantation has received some attentionand has been considered advantageous over the former methods because theimplantation energies required are less than 50% of that of oxygen ionimplants and the dosage required is two orders of magnitude lower.

U.S. Pat. No. 7,176,528 discloses a process that produces silicon onglass (SiOG) structure. The steps include: (i) exposing a silicon wafersurface to hydrogen ion implantation to create a bonding surface; (ii)bringing the bonding surface of the wafer into contact with a glasssubstrate; (iii) applying pressure, temperature and voltage to the waferand the glass substrate to facilitate bonding therebetween; (iv) coolingthe structure to a common temperature; and (v) separating the glasssubstrate and a thin layer of silicon from the silicon wafer.

Although the manufacturing processes for making SOI structures ismaturing, the commercial viability and/or application of final productsemploying them is limited by cost concerns. A significant cost inproducing an SOI structure using the process disclosed in U.S. Pat. No.7,176,528 is incurred during the ion implantation step. It is believedthat reductions in the cost of carrying out the ion implantation processwould improve the commercial application of SOI structures. Accordingly,it is desirable to continue to advance the efficiency of producing SOIstructures.

Among the areas of the ion implantation process where costs areexcessively high, include the resources required to prepare, and makeoperational, the sources of ions and the tools used for implantation.For example, when ion plasmas are employed to source ions forimplantation, some type of plasma generator is required, such as an arcchamber or the like. Significant resources (time, personnel, and money)are required to make an arc chamber ready and operational. In addition,there are significant costs associated with making the semiconductorwafer (the work piece to be implanted with ions) ready to receive theions. For example, some type of atmospheric control chamber (oftencalled an end station) is usually employed to establish desirableconditions for implantation. These conditions may include carefullycontrolling vacuum, temperature, humidity, cleanliness, etc. within thechamber. Again, significant resources (time, personnel, and money) arerequired to make the end station ready and operational for a given ionimplantation process.

The above cost issues are exacerbated when one is interested inimplanting more than one species of ion into a given semiconductorwafer. Indeed, one prior art approach to multiple ion speciesimplantation is to use a single machine approach (a single implanter setup with a single ion source) to implant one species of ion at a time.This typically involves setting up the source, accelerator equipment,and end station for one species of ion, implanting that species, andthen ramping down the set up, and repeating the setup for the nextspecies of ions. While the end station set up may remain through thetransition of ion species, the transition of the ion source (includingclearing the memory effect) from one species to another is very timeconsuming and costly.

An alternative system may employ a dual machine approach (two separateimplanters, each with a dedicated ion source) to implant one species ofion at a time. This typically involves setting up both sources andaccelerator equipment for both species of ion. The semiconductor waferis placed in one of the end stations, brought to the proper atmosphericconditions, and one of the ion species is implanted. Then thesemiconductor wafer is brought back to ambient conditions, transferredto the other end station, and brought back to the proper atmosphericconditions for the implantation of the second ion species. Thus, whilethe delays associated with transitioning a single source is reduced oreliminated, the cycling of the semiconductor wafer through two differentend stations is time consuming and costly. Since transport between twoend stations is required, the possibility of substrate contamination isalso significantly higher in the dual machine approach.

Therefore, irrespective of which approach is employed (single or dualmachine), the costs associated with preparing, and making operational,the ion sources and/or end stations used during the multiple ion speciesimplantation processes are excessive.

There have been advancements made to the prior art approach toimplanting more than one species of ion into a given semiconductorwafer. For example, one new approach is to implant both species of ionsinto the semiconductor wafer simultaneously. Details of this approachmay be found in co-owned and co-pending U.S. Ser. No. 12/709,833, filedFeb. 2, 2010, entitled SEMICONDUCTOR STRUCTURE MADE USING IMPROVED IONIMPLANTATION PROCESS, the entire disclosure of which is incorporatedherein in its entirety. While this new approach is very promising,additional research and advancements have been made, which are believedto provide reasonable alternatives, if not significant advantages, overthe foregoing processes.

In an alternative prior art system, which has been manufactured by acompany called Varian Inc., multiple end stations have been employedduring ion implantation in order to reduce lost time associated withloading, unloading, and re-loading semiconductor wafers during ionimplantation. In the Varian system, an ion beam was bent via a magnetand directed to a scanner, which was designed to produce two fanned-oution beams. The two fanned-out ion beams were not producedsimultaneously, but rather were produced in the alternative. In otherwords, the system was selectable in that the scanner could produce onebeam or the other, but not both at the same time. One beam, if selected,was sent in one direction to an angle correction mechanism, whichdirected the fanned-out beam perpendicularly to a first end-station. Theother beam, if selected, was sent in another direction to a separateangle correction mechanism, which directed the fanned-out beamperpendicularly to a second end-station. Thus, while the first beam wasselected, the second end-station could be unloaded and re-loaded withsemiconductor wafers, and vice verse. While this approach addressed someof the cost issues associated with ion implantation, it does not permitcost-effective ion implantation of multiple species of ions.

SUMMARY

Although the features, aspects and embodiments disclosed herein may bediscussed in relation to the manufacture of semiconductor-on-insulator(SOI) structures, skilled artisans will understand that such disclosureneed not be limited to SOI manufacturing. Indeed, the broadestprotectable features, aspects, etc. disclosed herein are applicable toany process in which ion implantation into (or onto) semiconductormaterial is required, whether such semiconductor material is used inconjunction with an insulator or otherwise.

For ease of presentation, however, the disclosure herein may be made inrelation to the manufacture of SOI structures. The specific referencesmade herein to SOI structures are to facilitate the explanation of thedisclosed embodiments and are not intended to, and should not beinterpreted as, limiting the scope of the claims in any way. The SOIabbreviation is used herein to refer to semiconductor-on-insulatorstructures in general, including, but not limited to,semiconductor-on-glass (SOG) structures, silicon-on-insulator (SOI)structures, and silicon-on-glass (SiOG) structures, which alsoencompasses silicon-on-glass-ceramic structures. In the context of thisdescription, SOI may also refer to semiconductor-on-semiconductorstructures, such as silicon-on-silicon structures, etc.

In accordance with one or more embodiments herein, methods and apparatusof forming a semiconductor structure, include: subjecting animplantation surface of a semiconductor wafer to an ion implantationprocess to create an exfoliation layer therein, wherein the ionimplantation process includes implanting two different species of ionsinto the implantation surface of the semiconductor wafer, each speciesbeing implanted serially, but within close temporal proximity to oneanother.

Other aspects, features, advantages, etc. will become apparent to oneskilled in the art when the description of the embodiments herein istaken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

For the purposes of illustrating the various aspects and featuresdisclosed herein, there are shown in the drawings forms that arepresently preferred, it being understood, however, that the coveredembodiments are not limited to the precise arrangements andinstrumentalities shown.

FIG. 1 is a block diagram illustrating the structure of a semiconductordevice in accordance with one or more embodiments disclosed herein;

FIGS. 2-5 are schematic diagrams illustrating intermediate structuresformed using processes of manufacturing the semiconductor device of FIG.1;

FIG. 6 is a simplified block diagram and schematic diagram of anapparatus (a dual beam implant tool) suitable for implanting a donorsemiconductor wafer with ions to produce an intermediate structureuseful in manufacturing the semiconductor device of FIG. 1.

FIGS. 7A-7B illustrate respective embodiments of a source of plasma,which simultaneously produces first plasma (including a first species ofions) and second plasma (including a second, differing, species ofions).

DETAILED DESCRIPTION

With reference to the drawings, wherein like numerals indicate likeelements, there is shown in FIG. 1 a semiconductor-on-substratestructure 100 in accordance with one or more embodiments disclosedherein. In order to provide some specific context in which to discussthe broadest protectable features and aspects disclosed herein, it willbe assumed that the semiconductor-on-substrate structure 100 is an SOIstructure, such as a semiconductor-on-glass structure.

The SOI structure 100 may include a substrate 102, and a semiconductorlayer 104. Such an SOI structure 100 may have suitable uses inconnection with fabricating thin film transistors (TFTs), e.g., fordisplay applications, including organic light-emitting diode (OLED)displays and liquid crystal displays (LCDs), integrated circuits,photovoltaic devices, etc. Although not required, the semiconductormaterial of the layer 104 may be in the form of a substantiallysingle-crystal material. The word “substantially” is used in describingthe layer 104 to take into account the fact that semiconductor materialsnormally contain at least some internal or surface defects eitherinherently or purposely added, such as lattice defects or a few grainboundaries. The word “substantially” also reflects the fact that certaindopants may distort or otherwise affect the crystal structure of thebulk semiconductor.

For the purposes of discussion, it is assumed that the semiconductorlayer 104 is formed from silicon. It is understood, however, that thesemiconductor material may be a silicon-based semiconductor or any othertype of semiconductor, such as, the III-V, II-IV, II-IV-V, etc. classesof semiconductors. Examples of these materials include: silicon (Si),germanium-doped silicon (SiGe), silicon carbide (SiC), germanium (Ge),gallium arsenide (GaAs), GaP, and InP.

The substrate 102, may be any desirable material exhibiting anydesirable characteristics. For example, in some embodiments, thesubstrate 102 may be formed from a semiconductor material, such as theabove-listed varieties.

In accordance with alternative embodiments, the substrate 102 may be aninsulator, such as glass, an oxide glass, or an oxide glass-ceramic. Asbetween oxide glasses and oxide glass-ceramics, the glass may have theadvantage of being simpler to manufacture, thus making them more widelyavailable and less expensive. By way of example, a glass substrate 102may be formed from glass containing alkaline-earth ions, such as,substrates made of CORNING INCORPORATED GLASS COMPOSITION NO. 1737 orCORNING INCORPORATED GLASS COMPOSITION NO. EAGLE 2000™. These glassmaterials have particular use in, for example, the production of liquidcrystal displays.

While the subject matter of particular interest herein involves ionimplantation into semiconductor material, it is believed that providingsome additional context in terms of a specific process for manufacturingthe SOI 100 is beneficial. Thus, reference is now made to FIGS. 2-5,which illustrate a general process (and resultant intermediatestructures) within which the aforementioned ion implantation may becarried out in order to manufacture the SOI structure 100 of FIG. 1.

Turning first to FIG. 2, a donor semiconductor wafer 120 is prepared,such as by polishing, cleaning, etc. to produce a relatively flat anduniform implantation surface 121 suitable for bonding to the substrate102, e.g., a glass or glass-ceramic substrate. For the purposes ofdiscussion, the semiconductor wafer 120 may be a substantially singlecrystal Si wafer, although as discussed above any other suitablesemiconductor conductor material may be employed.

An exfoliation layer 122 is created by subjecting the implantationsurface 121 to an ion implantation process to create a weakened region123 below the implantation surface 121 of the donor semiconductor wafer120. Although it is this ion implantation process that is the focus ofthe disclosure herein, at this point only general reference will be madeto the process for creating the weakened region 123. Later in thisdescription, however, a more detailed discussion of one or more ionimplantation processes of specific interest will be provided. The ionimplantation energy may be adjusted using to achieve a general thicknessof the exfoliation layer 122, such as between about 300-500 nm, althoughany reasonable thickness may be achieved. The effect of ion implantationinto the donor semiconductor wafer 120 is the displacement of atoms inthe crystal lattice from their regular locations. When the atom in thelattice is hit by an ion, the atom is forced out of position and aprimary defect, a vacancy and an interstitial atom, is created, which iscalled a Frenkel pair. If the implantation is performed near roomtemperature, the components of the primary defect move and create manytypes of secondary defects, such as vacancy clusters, etc.

With reference to FIG. 3, the substrate 102 may be bonded to theexfoliation layer 122 using an electrolysis process (also referred toherein as an anodic bonding process). A basis for a suitableelectrolysis bonding process may be found in U.S. Pat. No. 7,176,528,the entire disclosure of which is hereby incorporated by reference.Portions of this process are discussed below; however, one or moreembodiments described herein are directed to modifications of the ionimplantation process of U.S. Pat. No. 7,176,528.

In the bonding process, appropriate surface cleaning of the substrate102 (and the exfoliation layer 122 if not done already) may be carriedout. Thereafter, the intermediate structures are brought into direct orindirect contact. The resulting intermediate structure is thus a stack,including the bulk material layer of the donor semiconductor wafer 120,the exfoliation layer 122, and the glass substrate 102.

Prior to or after the contact, the stack of the donor semiconductorwafer 120, the exfoliation layer 122, and the glass substrate 102 isheated (indicated by the arrows in FIG. 3). The glass substrate 102 andthe donor semiconductor wafer 120 are taken to a temperature sufficientto induce ion migration within the stack and an anodic bondtherebetween. The temperature is dependent on the semiconductor materialof the donor wafer 120 and the characteristics of the glass substrate102. By way of example, the temperature of the junction may be taken towithin about +/−350° C. of a strain point of the glass substrate 102,more particularly between about −250° C. and 0° C. of the strain point,and/or between about −100° C. and −50° C. of the strain point. Dependingon the type of glass, such temperature may be in the range of about500-600° C.

In addition to the above-discussed temperature characteristics,mechanical pressure (indicated by the arrows in FIG. 3) is applied tothe intermediate assembly. The pressure range may be between about 1 toabout 50 psi. Application of higher pressures, e.g., pressures above 100psi, might cause breakage of the glass substrate 102.

A voltage (indicated by the arrows in FIG. 3) is also applied across theintermediate assembly, for example with the donor semiconductor wafer120 at the positive electrode and the glass substrate 102 the negativeelectrode. The application of the voltage potential causes alkali oralkaline earth ions in the glass substrate 102 to move away from thesemiconductor/glass interface further into the glass substrate 102. Moreparticularly, positive ions of the glass substrate 102, includingsubstantially all modifier positive ions, migrate away from the highervoltage potential of the donor semiconductor wafer 120, forming: (1) areduced positive ion concentration layer in the glass substrate 102adjacent the exfoliation layer 122; and (2) an enhanced positive ionconcentration layer of the glass substrate 102 adjacent the reducedpositive ion concentration layer. This formation results in barrierfunctionality, i.e., preventing positive ion migration back from theoxide glass or oxide glass-ceramic, through the reduced positive ionconcentration layer, and into the semiconductor layer.

With reference to FIG. 4, after the intermediate assembly is held underthe conditions of temperature, pressure and voltage for a sufficienttime, the voltage is removed and the intermediate assembly is allowed tocool to room temperature. At some point during heating, during a dwell,during cooling, and/or after cooling, the donor semiconductor wafer 120and the glass substrate 102 are separated. This may include some peelingif the exfoliation layer 122 has not already become completely free fromthe donor 120. The result is a glass substrate 102 with the relativelythin exfoliation layer 122 formed of the semiconductor material of thedonor semiconductor layer 120 bonded thereto. The separation may beaccomplished via fracture of the exfoliation layer 122 due to thermalstresses. Alternatively or in addition, mechanical stresses such aswater jet cutting or chemical etching may be used to facilitate theseparation.

The cleaved surface 125 of the SOI structure 100, just afterexfoliation, may exhibit surface roughness, excessive silicon layerthickness, and/or implantation damage of the silicon layer (e.g., due tothe formation of an amorphized silicon layer). Depending on theimplantation energy and implantation time, the thickness of theexfoliation layer 122 may be on the order of about 300-500 nm, althoughother thicknesses may also be suitable. These characteristics may bealtered using post bonding processes in order to advance from theexfoliation layer 122 and produce the desirable characteristics of thesemiconductor layer 104 (FIG. 1). It is noted that the donorsemiconductor wafer 120 may be reused to continue producing other SOIstructures 100.

Reference is now made to FIG. 5, which is again directed to the creationof the exfoliation layer 122 by subjecting the implantation surface 121of the donor semiconductor wafer 120 to an ion implantation process tocreate the weakened region 123 below the implantation surface 121 of thedonor semiconductor wafer 120. In accordance with one or moreembodiments, the ion implantation process includes implanting twodifferent species of ions into the implantation surface 121 of the donorsemiconductor wafer 120. In accordance with preferred aspects, the twodifferent species of ions are implanted one after the other, serially,using an improved apparatus and process.

With reference to FIG. 6, the implantation of the two different types ofions may be carried out in a multiple beam implant tool 150. Although apreferred implementation includes two simultaneous ion beams (as shown),those skilled in the art will appreciate that the inventive aspects maybe extended to produce tools with more beams, such as three or morebeams. The tool 150 may be purchased commercially and then modified toachieve the process described herein, or a substantially new tool may bedeveloped. As the design and operating principle of implant tools maydiffer, the specific modifications in equipment and/or operation will beleft to the skilled artisan, but should be based on the descriptionherein.

The ion implant tool 150 of FIG. 6 is illustrated in high-levelschematic form and includes a source 152 of plasma, which simultaneouslyproduces first plasma (including a first species of ions) and secondplasma (including a second, differing, species of ions). Thisfunctionality of the source 152 is illustrated by way of two inputs 202,204, which represent the precursor sources of differing ions.

With reference to FIGS. 7A and 7B, the source 152 may be implemented inany number of ways. For example, with reference to FIG. 7A, the source152 may include first and second sources of gas vapor, e.g. a first tank202 and a second tank 204, each feeding a single chamber 202A. The gasvapor is required for plasma generation in the chamber 202A. The tanks202 may contain gases, liquids or solids. For liquids and solids a levelof heating is required to generate the gas vapor. The respective gasflows from the tanks 202 are controlled via needle valves or mass-flowcontrollers. The gases, liquids or solids within the tanks 202, 204include a respective species of atoms and/or molecules. By way ofexample, the first tank 202 may contain atoms and/or molecules ofhydrogen, and the second tank 204 may contain atoms and/or molecules ofhelium. Other atom/molecule species are also possible, such as beingtaken from the group consisting of: boron, hydrogen, helium, and/orother suitable species of atoms and/or molecules.

In an alternative configuration, the source 152 of FIG. 7A may notinclude both tanks of gas 202, 204, but instead may employ a single tankcontaining both species of atoms and/or molecules, e.g., hydrogen andhelium mixed within the tank.

In accordance with one or more embodiments, the chamber 202A may includethe structural elements necessary to produce plasma from the input gas.For example, the first chamber 202A may be implemented as an arcchamber, which includes the magnets, filaments, reflectors, energysources, etc. necessary to receive the gas from the tanks 202, 204 (orthe single tank) and produce plasma. It is understood, however, that anyother suitable and known technique for producing plasma from gas mayadditionally or alternatively be employed. In this embodiment, thesingle chamber produces a single stream of plasma, containing the firstand second plasma (i.e., containing both species of ions). It isunderstood that those skilled in the art are well aware of the basicstructural elements necessary to produce plasma from gas within an arcchamber. Those skilled in the art will appreciate that, depending on thespecies of atoms and/or molecules within the gas, the resulting plasmamay include differing types of ions, while still being within a species.For example, in the case of hydrogen, the plasma may include H ions, H₂ions, and H₃ ions. In the case of helium, the plasma may includesubstantially only He₄ ions. In a combined plasma stream of both thefirst and second plasma, the stream will include both ion species, forexample, H ions, H₂ ions, H₃ ions, and He₄ ions.

With reference to FIG. 7B, an alternative embodiment of the source 152may include the first and second sources of gas, e.g. the first tank 202and the second tank 204, each feeding a respective chamber 202A, 204A.In accordance with this embodiment, both of the respective chambers202A, 204A include the magnets, filaments, reflectors, energy sources,etc. necessary to receive the gas from the respective tank 202, 204 andproduce two, separate streams of plasma, the first plasma and the secondplasma. Thus, the first plasma, which includes a first species of ions,may be produced within the first chamber 202A, and the second plasma,which includes a second, differing, species of ions, may be producedwithin the second chamber 204A.

As discussed above, those skilled in the art will appreciate that thereis a substantial amount of time needed to ramp up a chamber from a coldstart to a status suitable for producing high density plasma. Indeed,set up time includes adjustments for the species of ion, and themagnets, filaments, reflectors, energy sources, etc. must all ramp upand settle into proper conditions for plasma generation. As will bediscussed further herein, when a single chamber 202A is used to producea single stream of plasma (containing both species of ions) there isonly one set up time (which may include the associated memory effects),and no time is lost switching over from one species of ion to another.When multiple chambers 202A, 204A are employed, each of the chambers maybe simultaneously ramped up and each may produce plasma at the sametime. Again, there is effectively only one set up time (both chambersbeing set up in parallel), and no time is lost switching over from onespecies of ion to another (which eliminates the delays associated withramping up, including the memory effects). This permits rapid deliveryof the differing species of ions to the semiconductor wafer 120 duringion implantation, thereby resulting in significant cost savingadvantages, which will be discussed further with relation to otheraspects of the system 150 that have yet to be presented.

The source 152 is in communication with the next phase of the system150, which is an accelerator system 170. The output of the source 156(whether a combined plasma stream or two separate streams) is incommunication with an input (or inlet) 172 of the accelerator system170. The accelerator system 170 simultaneously accelerates the first andsecond plasma along an initial axis, A0, from the source 152. Morespecifically, the accelerator system 170 includes any number ofelectrodes, two such electrodes 208, 210 being shown by way of example.An appropriate voltage potential (which may be in the range of 10's to100's of K volts) between the electrodes 208, 210 will cause the firstand second plasma to accelerate toward and through the analyzer magnet180.

The analyzer magnet 180 alters the trajectory of the ions within theplasma. The change in trajectory of the ions within the first and secondplasma will depend on a number of factors, including the strength of themagnetic field produced by the analyzer magnet 180, the mass/chargeratio of the ions, the acceleration magnitude of the ions as they passthrough the magnet 180, etc., all of which are known in the art.

The accelerator system 170 applies the same electric field (of a givenmagnitude) to both the first and second plasma, thereby accelerating therespective first and second species of ions to velocities that exhibitdiffering momentum. Indeed, recall that whether the first and secondplasma is in a single stream of in separate streams, once they are inthe accelerator system 170, the electric field is applied to all theions, which include, for example, H ions, H₂ ions, H₃ ions, and He₄ions. Each of these types of ions is of a differing mass, and thereforeeach of the types of ions will achieve a different momentum (whether ofdiffering velocity or not) through the analyzer magnet 180.

The analyzer magnet 180 applies a given magnetic field to both the firstand second species of ions. Since the different species of ions havedifferent momentums, the given magnetic force alters the trajectories ofthe respective first and second species of ions by differing amounts.Thus, the analyzer magnet 180 alters the trajectory of the first speciesof ions from the first plasma, producing at least one first ion beamalong a first axis, A1, which is transverse to the initial axis, A0.Simultaneously, the analyzer magnet 180 alters the trajectory of thesecond species of ions from the second plasma, producing at least onesecond ion beam along a second axis, A2, which is transverse to theinitial axis A0 and the first axis A1. Even within a species, such ashydrogen ions, there may be differing numbers of atomic bonds betweenatoms and thus, the resulting H ions, H₂ ions, and H₃ ions will eachhave a differing momentum. Likewise, the He₄ ions will have a differentmomentum than the hydrogen ions. Thus, the H ions, H₂ ions, H₃ ions, andHe₄ ions leave the analyzer magnet 180 at differing trajectories. Forpurposes of example, it is assumed that the desired ion species forimplanting the semiconductor wafer 120 are H₂ ions and He₄ ions, theelectric field, magnetic force, etc. are set such that the H₂ ionsattain the trajectory along the first axis A1 and the He₄ ions attainthe trajectory along the second axis A2.

The system 150 includes a beam processing system 250 operating tosimultaneously direct the first and second ion beams toward thesemiconductor wafer 120 such that the first and second species of ionsbombard the implantation surface 121 of the semiconductor wafer 120 tocreate the exfoliation layer 122 therein.

The beam processing system 250 includes a mass resolution system 252,which includes a number of slits, at least one slit for each species ofions to be delivered to the semiconductor wafer 120. In the illustratedexample, there are two such slits 252A, and 252B. The slit 252A ispositioned to permit the first ion beam traveling along axis A1 to passtherethrough. The slit 252B is positioned to permit the second ion beamtraveling along axis A2 to pass therethrough. The other trajectories ofthe ions not being used cause the respective beams to terminate intofull stops, such as the beam traveling along axis A3. In keeping withthe examples discussed above, the beam traveling along axis A3 might beH₃.

The beam processing system 250 also includes a scanner system, whichincludes a plurality of scanner elements, two scanner elements 254A,254B being shown in this example. The first scanner element 254Areceives the first ion beam along the first axis A1 and fans the firstion beam out 256A in one dimension (e.g., in one plane). Similarly, thesecond scanner element 254B receives the second ion beam along thesecond axis A2 and fans the second ion beam out 256B in similardimension. The respective scanner elements 254A, 254B are incommunication with respective angle correction elements 258A, 258B. Thefirst angle correction element 258A operates to receive the fanned firstion beam 256A and re-direct same 260A in a direction substantiallyperpendicular (or other chosen angle) to the implantation surface 121 ofthe semiconductor wafer 120. Similarly, the second angle correctionelement 258B operates to receive the fanned second ion beam 256B andre-direct same 260B in a direction also substantially perpendicular (orother chosen angle) to the implantation surface 121 of the semiconductorwafer 120.

Notably, the first and second beams 260A, 260B are simultaneouslydelivered toward the semiconductor wafer 120, however, as will bediscussed below, they may not be simultaneously incident on the locationof the implantation surface 121 of the semiconductor wafer 120 at thesame time, but rather incident serially on a given portion of thesemiconductor wafer 120. In this regard, the beam processing system 250may further include some acceleration mechanisms (not shown) toaccelerate at least one of: the first ion beam along A1, the second ionbeam along A2, the first fanned ion beam 256A, the second fanned ionbeam 256B, the first re-directed beam 260A, and the second re-directedbeam 260B, toward the semiconductor wafer 120. Only one ion beam (onefor each ion specie) needs to be adjusted (typically reduced) so thatthe desired dose for each implanted specie is correctly maintained forthe scans required to complete the slowest implant time.

Individual ion beam energies are maintained by providing specific andseparate ion acceleration forces (e.g., via the aforementionedacceleration mechanisms) for each ion beam within the beam processingsystem 250 (post analyzer magnet 180).

The system 150 also includes an end station 190 operating to support andtranslate the semiconductor wafer 120 such that the first and secondspecies of ions, separately and serially, bombard the implantationsurface 121 to create the exfoliation layer 122 therein. The end station190 includes a transport mechanism 212, which permits the semiconductorwafer 120 to translate, or scan, (see the bi-directional arrow) inappropriate directions, such that the respective ion beams paint thesemiconductor wafer 120 and suitable target doses (one for each ionspecies) are achieved. In an alternative end station configuration,rotating process disks may be employed to rotate the semiconductor wafer120 through the ion beams, as opposed to the relatively lineartranslation of the semiconductor wafer shown in FIG. 6.

The end station 190 also operates to maintain a controlled atmospherewithin which the semiconductor wafer 120 is disposed duringimplantation. Preferably, the atmosphere includes a suitable vacuum,temperature, humidity, cleanliness, etc. In this regard, the end station190 includes an input in communication with the output from theaccelerator system 170, whereby the ion beams 260A, 260B may bereceived, but the controlled atmosphere is not lost.

The end station 190 operates to maintain the semiconductor wafer 120within the controlled atmosphere during the implantation of the firstion species 260A, and during a subsequent implantation of the second ionspecies 260B.

The ability to implant two differing species of ions in parallel, eachat chosen implant recipes, saves considerable time, and reducesproduction costs. Further, the single or multiple chambers 202A, 204Aare operating during the entire implantation process, which results invery significant cost and time savings.

While the above embodiments have been discussed with specific referenceto the structure of the tool 150, one skilled in the art will appreciatethat inventive aspects apply to one or more processes as well.

In this regard, a method of forming a semiconductor structure mayinclude: providing a first source of plasma (first plasma), whichincludes a first species of ions; providing a second source of plasma(second plasma), which includes a second, differing, species of ions;simultaneously accelerating the first and second plasma along an initialaxis; altering a trajectory of the first species of ions from the firstplasma, thereby producing at least one first ion beam along a firstaxis, which is transverse to the initial axis; altering a trajectory ofthe second species of ions from the second plasma, thereby producing atleast one second ion beam along a second axis, which is transverse tothe initial axis and the first axis; and simultaneously directing thefirst and second ion beams toward a semiconductor wafer such that thefirst and second species of ions serially bombard an implantationsurface of the semiconductor wafer to create an exfoliation layertherein.

The method may include supporting and translating the semiconductorwafer such that the first and second species of ions, separately andserially, bombard the implantation surface of the semiconductor wafer tocreate the exfoliation layer therein. The method may include translatingthe semiconductor wafer through the first ion beam and thereaftertranslating the semiconductor wafer through the second ion beam. Thesemiconductor wafer is maintained in a controlled atmosphere duringimplantation.

The method may further include fanning the first ion beam along thefirst axis into a fanned first ion beam, and re-directing the first ionbeam from the first axis to a direction substantially perpendicular to(or at another chosen incident angle) the implantation surface of thesemiconductor wafer. Similarly, the method may include fanning thesecond ion beam along the second axis into a fanned second ion beam, andre-directing the second ion beam from the second axis to the directionsubstantially perpendicular to (or at another chosen incident angle) theimplantation surface of the semiconductor wafer.

Although the aspects, features, and embodiments disclosed herein havebeen described with reference to particular details, it is to beunderstood that these details are merely illustrative of broaderprinciples and applications. It is therefore to be understood thatnumerous modifications may be made to the illustrative embodiments andthat other arrangements may be devised without departing from the spiritand scope of the appended claims.

The invention claimed is:
 1. An apparatus, comprising: a sourcesimultaneously producing first plasma, which includes a first species ofions, and second plasma, which includes a second, differing, species ofions; an accelerator system including an analyzer magnet, whichcooperate to simultaneously: (i) accelerate the first and second plasmaalong an initial axis, (ii) alter a trajectory of the first species ofions from the first plasma, thereby producing at least one first ionbeam along a first axis, which is transverse to the initial axis, and(iii) alter a trajectory of the second species of ions from the secondplasma, thereby producing at least one second ion beam along a secondaxis, which is transverse to the initial axis and the first axis; and abeam processing system operating to simultaneously direct the first andsecond ion beams toward a semiconductor wafer such that the first andsecond species of ions bombard an implantation surface of thesemiconductor wafer to create an exfoliation layer therein.
 2. Theapparatus of claim 1, wherein the first and second plasma are one of:combined into a single stream of plasma, and separate streams of plasma.3. The apparatus of claim 1, further comprising: an end stationoperating to support and translate the semiconductor wafer such that thefirst and second species of ions, separately and serially, bombard theimplantation surface of the semiconductor wafer to create theexfoliation layer therein.
 4. The apparatus of claim 2, wherein at leastone of: the end station translates the semiconductor wafer through thefirst ion beam and thereafter the end station translates thesemiconductor wafer through the second ion beam; and the end stationoperates to maintain a controlled atmosphere within which thesemiconductor wafer is disposed during implantation.
 5. The apparatus ofclaim 1, wherein: the accelerator system applies an electric field of agiven magnitude to both the first and second plasma, therebyaccelerating the respective first and second species of ions todiffering velocities; and the analyzer magnet system applies a givenmagnetic field to both the first and second species of ions, therebyaltering trajectories of the respective first and second species of ionsby differing amounts to attain the transverse first and second axes ofdirection.
 6. The apparatus of claim 5, further comprising: a firstscanner element operating to receive the first ion beam along the firstaxis and to fan the first ion beam out; and a second scanner elementoperating to receive the second ion beam along the second axis and tofan the second ion beam out.
 7. The apparatus of claim 6, furthercomprising: a first angle correction element operating to receive thefanned first ion beam and re-direct same in a selected directionsubstantially toward the implantation surface of the semiconductorwafer; and a second angle correction element operating to receive thefanned second ion beam and re-direct same in a selected directionsubstantially toward the implantation surface of the semiconductorwafer.
 8. The apparatus of claim 1, wherein the beam processing systemfurther operates to accelerate at least one of: the first ion beam, thesecond ion beam, the first fanned ion beam, the second fanned ion beam,the first re-directed beam, and the second re-directed beam, toward thesemiconductor wafer.
 9. The apparatus of claim 1, wherein the source ofplasma includes: a source of a first species of atoms and/or moleculesin communication with a first chamber, the first chamber operating toproduce the first plasma from the first species of atoms and/ormolecules; and a source of a second species of atoms and/or molecules incommunication with a second chamber, the second chamber operating toproduce the second plasma from the second species of atoms and/ormolecules.
 10. The apparatus of claim 9, wherein sources of the firstand second species of atoms and/or molecules are separate containers ofgas.
 11. The apparatus of claim 1, wherein the source of plasmaincludes: a source of a first species of atoms and/or molecules incommunication with a chamber; and a source of a second species of atomsand/or molecules in communication with the chamber, wherein the chamberoperates to produce the first and second plasma from the first andsecond species of atoms and/or molecules.
 12. The apparatus of claim 11,wherein sources of the first and second species of atoms and/ormolecules are separate containers of gas.
 13. The apparatus of claim 1,wherein the first and second species of ions are taken from the groupconsisting of: boron, hydrogen, and helium.
 14. A method of forming asemiconductor structure, comprising: providing a first source of plasma(first plasma), which includes a first species of ions; providing asecond source of plasma (second plasma), which includes a second,differing, species of ions; simultaneously accelerating the first andsecond plasma along an initial axis; altering a trajectory of the firstspecies of ions from the first plasma, thereby producing at least onefirst ion beam along a first axis, which is transverse to the initialaxis; altering a trajectory of the second species of ions from thesecond plasma, thereby producing at least one second ion beam along asecond axis, which is transverse to the initial axis and the first axis;and simultaneously directing the first and second ion beams toward asemiconductor wafer such that the first and second species of ionsserially bombard an implantation surface of the semiconductor wafer tocreate an exfoliation layer therein.
 15. The method of claim 14, furthercomprising: supporting and translating the semiconductor wafer such thatthe first and second species of ions, separately and serially, bombardthe implantation surface of the semiconductor wafer to create theexfoliation layer therein.
 16. The method of claim 15, furthercomprising translating the semiconductor wafer through the first ionbeam and thereafter translating the semiconductor wafer through thesecond ion beam.
 17. The method of claim 16, further comprisingmaintaining the semiconductor wafer in a controlled atmosphere duringimplantation.
 18. The method of claim 14, further comprising: fanningthe first ion beam along the first axis into a fanned first ion beam;and fanning the second ion beam along the second axis into a fannedsecond ion beam.
 19. The method of claim 14, further comprising:re-directing the first ion beam from the first axis to a selecteddirection substantially toward the implantation surface of thesemiconductor wafer; and re-directing the second ion beam from thesecond axis to the selected direction substantially toward theimplantation surface of the semiconductor wafer.
 20. The method of claim14, wherein the first and second species of ions are taken from thegroup consisting of: boron, hydrogen, and helium.